My Bull Bar's got a Severe Shake! Anyone else?

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Reddirtearth
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My Bull Bar's got a Severe Shake! Anyone else?

Unread post by Reddirtearth » February 11th, 2017, 10:25 pm

Just installed Lightforce HTX lights to the bullbar.
The Bull bar shakes like crazy and gives me a headache with the lights flickering, all connections are tight, firm and good.
Anyone had this issue?
oh and car has only done 2500km

Dmaxqld
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Re: My Bull Bar's got a Severe Shake! Anyone else?

Unread post by Dmaxqld » February 12th, 2017, 4:55 am

Dmax cab is rubber mounted. Bullbar is solid mounted to chassis. There is a far bit of cabin flex so bullbar appears to be shaking but it is in fact the cabin moving around on its rubber mounts. My lights do not shake any more than they did on previous vehicles.

Peter Aawen
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Re: My Bull Bar's got a Severe Shake! Anyone else?

Unread post by Peter Aawen » February 12th, 2017, 7:42 am

Dmaxqld wrote:Dmax cab is rubber mounted. Bullbar is solid mounted to chassis....
And for that reason you really need to check the chassis section it all mounts onto as well as how tight the bolts are, just to make sure the chassis isn't flexing under the weight of the bar & anything else you have mounted on it!! Some bars have been known to fall off, taking chunks of chassis with them!

So how do you confirm the chassis isn't flexing too?? Check the bolts, sure, but then park your vehicle a few metres in front of & facing a wall or the shed door & turn the lights on, then get out smack the bar hard with your hand. Some shake is to be expected, especially if you've got the lights mounted on the bar a fair way away from the actual bar mounts; but if your lights are mounted onto the bar down close to the bar mounts/chassis rails, there really shouldn't be a heap & a little vibration shouldn't be a problem. Altho the apparent vibration caused by the differences between the body & the bar/lights movement that Dmaxqld mentioned can make it APPEAR bloody awful while you are driving along, especially on rough roads that make the body mounts work hard to give you that smooooth ride!!

Buuut, if you've got the lights mounted on the top of the top rail of the bull bar, then more fool you - the greater the distance from the bull bar's chassis mounts to the light mounts means the relatively light weight lights have more leverage, creating more vibration in the first place, AND they end up getting greater movement distance from the smaller frequency vibrations that occur down at the chassis mount level, so you'll probably hafta learn to live with that - or mount your lights down lower & closer to the chassis rails! ;)

Good Luck! :thumb:
An Ex-Service person is someone who thought enough about their country & how great it is, how lucky we are to live here, to write a blank cheque made out to 'The People and Commonwealth of Australia' for the value of 'Up to & including my Life!'

Peter Aawen
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Re: My Bull Bar's got a Severe Shake! Anyone else?

Unread post by Peter Aawen » February 12th, 2017, 8:10 am

Dmaxqld wrote:Dmax cab is rubber mounted. Bullbar is solid mounted to chassis. ......

Wot he says!! ^^ So don't just check the tightness of the bolts, also check the whole section of metal they mount onto - look for cracks or marks/cracking paint, flexing etc right back a half a metre or so into both sides of the chassis rails to exclude any issues there! And then check to see if the vibration is really in the bar, or is it just the 'appearance' of vibration that Dmaxqld suggests??!? That appearance thing can be bloody awful, but it's far less awful than having your bar drop off onto the road at speed taking a couple of chunks of chassis rail with it!! And that has been more prevalent in the last decade, especially since air bag crush cans & then progressive crumple zones were built into the vehicles' chassis rails instead of into the bull bar or front bumper mounts, so even tho I don't know which method the Dmax's use, it's really worth checking!! ;)

How do you do that?? Do all the bolt tightening & light mount checking you want, then park your vehicle facing & about 3 metres from a wall or shed door & turn your lights ON so you can see the bright spots they make on the wall; then get out & hit the top rail of the bull bar with the flat of your hand - as HARD as you can! Watch the wall to see how bad the vibrations really are - there WILL be some, but if your lights are mounted onto the bar down fairly close to the bull bar's mounting points onto the chassis, there shouldn't be a heap of vibration. Couple of inches total amplitude for a second or two max. If there is anything much more than that & your lights are mounted down low in the bull bar, then you should check the light globes in the lights themselves, the light mounts, the bull bar, bull bar mounts, & the chassis mounts or rails for a cause.

Buuut, if you've got your lights mounted up high on the bar, well away from where the bar mounts to the chassis, maybe even on the top rail of the bull bar, more fool you - you'll probably hafta learn to live with that vibration (or move the lights!) Why is this so?? It's fairly simple really, the closer your lights are mounted to the chassis mounts for the bull bar, the less impact any vibration in the bar will have on them, because the leverage they can place on or get from the bar is very small & the frequency & amplitude of any vibration will be correspondingly small. The further away you take your light mounting position from the bull bar chassis mounts, the greater the leverage they place on the bar & the greater the amplitude they'll reflect from any vibrations caused by whatever reason in the bar!! The absolute worse place for vibrations that you can put lights is on top of the top rail of the bull bar so they are above the bonnet level, cos they'll get all that previously mentioned stuff, PLUS a heap of extra vibration caused by the airflow & wind gusts etc as you drive!! ;)

Over to you, Good Luck! :thumb:
An Ex-Service person is someone who thought enough about their country & how great it is, how lucky we are to live here, to write a blank cheque made out to 'The People and Commonwealth of Australia' for the value of 'Up to & including my Life!'

mydmax
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Re: My Bull Bar's got a Severe Shake! Anyone else?

Unread post by mydmax » February 12th, 2017, 10:24 am

All crumple zone chassis will move slightly and because the bar is mounted out front it will oscillate a little. Haven't seen Crush cans for vehicle since the early RangeRovers where they had a Can on each side of the bumper bar. So I think all is crumple zones for the last 15years at least. People used to hit the crush can with a hammer and watch the bag deploy, sort of party trick. All sensing now is done by decelerometers which fire the bag only when the power is on.

Are the Lights in question poly/plastic bodies and mounting base plastic too? If so they will flex enough to spray light if the bar is creating a frequency.
As mentioned, lights mounted away from the chassis area will have more and more ability to flex and walk about particularly on rough roads.
Do the lights have a brace from the body to stop oscillations?

Reddirtearth
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Re: My Bull Bar's got a Severe Shake! Anyone else?

Unread post by Reddirtearth » February 16th, 2017, 9:05 pm

Problem has been fixed

cheers for the reply messages.

rang arb and they said to bring it in for a check over.
the bullbar is solid mounted, the lights are firmly done up, the bullbar has no movement, all is good.
the issue is that where the lights get mounted there is the very thin metal used in this area. Therefore the lights amplified the vibrations.

ARB have addressed the issue and are in the process of making a custom plate to fit in the area, thick enough to make it solid eliminating the lights from shuddering.

many thanks to every ones input
And a big shout out to ARB for looking after their customers, only brings us back for more goodies!

typhoeus
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Re: My Bull Bar's got a Severe Shake! Anyone else?

Unread post by typhoeus » February 17th, 2017, 5:59 pm

makes you wonder how much of a hit it would take if a couple of spotties make the metal flex that much. It seems that bull-bars these days are almost cosmetic, or ornamental, and if its a new vehicle, you cant do anything about it and stay legal :(

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